free choice of providers and hospitals but require out-of-pocket spending (deductibles) by the consumer before coverage under the plan, cost-sharing when the plan does provide coverage (flat dollar copayments or coinsurance payments), and different levels of coverage for the same service when acquired in-network versus out-of-network. PPO insurance arrangements now cover more than 58% of all persons who have employment-based health insurance (Figure 4-2).

Coverage for hepatitis B and other ACIP-recommended vaccinations is routine in HMOs but variable in PPOs and other private insurance plans. There is little or no cost-sharing for vaccinations and other preventive services in HMOs, whereas it is greater in PPOs and other health plans because of applicable deductibles and coinsurance or copayments. Cost-sharing is greatest in health plans that have very high deductibles (high-deductible health plans, HDHPs). In 2008, 8% of all privately insured Americans were covered by HDHPs with annual deductibles of $1,000 or more (Kaiser Family Foundation and HRET, 2008). HDHPs can pose formidable barriers to preventive care and vaccination unless these services are specifically exempted from the deductible or enrollees are provided a separate source of funds to pay for them (for example, a reimbursement arrangement or a